| 摘要 |
PURPOSE:To make the miniaturization and light weight of the captioned device, and to improve effectiveness and an action stableness by providing a lighting current control circuit for controlling a high frequency intermission action of a switching element and a lighting current after lighting as well as connecting a preheating/high pressure pulse generation circuit to a fluorescent lamp in parallel. CONSTITUTION:A fluorescent lamp 4 is lit with voltage applied between heaters of the lamp 4 by an intermission action with a switching element 3 during an electric source voltage is above the break over voltage of a slidac 61 in an actuating action. After lighting, a preheating/high pressure pulse generation circuit 6 is automatically opened since a lamp voltage of the lamp 4 becomes below an action voltage of the slidac 61. A lighting current after lighting is fixedly controlled with a lighting current control circuit 5 controlling a current- limiting inductor 2 and switching element 3 by a frequency modulation control method in which an off-time width is prescribed. As a result, a circuit constitution can be simple, effectiveness high, and the action stableness ensured for the sudden variation of current, etc. |
